var a='\x41'
console.log(a)
var a1='\u4e2d\u6587'
console.log(a1)

var b="i'm ok"
console.log(b)
var c='i\'m \"ok\"!'
console.log(c)

console.log('春眠不\n觉晓\n处处闻啼\n鸟')
console.log(`春眠不
觉晓
处处闻啼
鸟`)

var name = '小明';
var age = '15';
var zong ='你好，' + name + ',你今年' + age + '岁了';
console.log(alert(zong));
var name = '小明';
var age = '15';
console.log('你好，${name},你今年${age}岁了！')

var s ='Hello, world!'
console.log(s.length);
console.log(s[0]);   
console.log(s[6]);   
console.log(s[7]);   
console.log(s[12]); 
console.log(s[13]);

var w ='Text';
w[0]='X';
alert(w);

var q='Hello';
console.log(q.toUpperCase());

var e='Hello';
console.log(e.toLowerCase());


var t='hello world';
t.indexOf('world');
t.indexOf('World');